Are you engraving or cutting?

Your intended application is the primary factor for determining the power of your laser. Are you looking to engrave material or are you looking to cut it? If you’re looking to engrave or etch mate­rial, a 500 mW diode laser may be sufficient, but if you want to cut material other than paper you’ll need a more powerful unit. The more powerful the laser, the faster and deeper it will engrave or cut. A general rule of rule of thumb in the industry is 10 watts of power for every millimetre of material to be cut. However, more power also means more money. To offset the cost, you can achieve the cut­ting performance of a stronger laser by reducing your feed speed (allowing the laser more time to “burn” through material) or per­forming multiple cutting passes for a project.

Diode lasers

Diode lasers generally have a maximum power rating of 10W and consist of a laser unit, control board and power supply. Due to the enclosed and compact nature of diode lasers, they’re often used as desktop machines or are easily added onto an existing CNC machine. If you’re considering a laser as an add-on to a CNC unit, you need to be aware of the increased PPE required for their opera­tion. Diode lasers generally range in price from $150 to $4,500, depending on the power and if it’s a stand-alone unit.

CO2 lasers

In comparison, CO2 lasers for woodworking typically have power ranges from 20W and up. This increase in power allows for faster production speed and thickness of material to cut. These units are fully enclosed with interlocked lids specifically designed to block the wavelength of light produced by the laser for added safety. With the increase in power also comes additional requirements for cool­ing of the laser tube and exhaust and filtration of the laser bed. Generally, CO2 lasers range from approximately $5,000 to $40,000.

Materials to work with

Now we need to explore how material can impact a laser’s per­formance. Lasers can be used to engrave or cut a wide variety of material, such as any paper product, fabric, leather, all types of wood, plastics and acrylics. The type of material you’re using will have a significant impact on your laser’s performance. Physical characteristics like grain orientation and knots also will impact the overall performance of your laser. With lasers you also need to be acutely aware of the chemical composition of your material. Lasers burn material, which is a chemical process that often produces smoke. Generally, unfinished natural materials pose limited risk to users. However, adhesives, finishes and manufactured products that contain polyvinyl chloride may release chlorine gas when lasered. So, under no circumstances, should you use a laser on material if you’re unsure of its chemical composition. If you have doubts about the suitability of material for lasering, laser suppliers may be able to provide material safety data sheets for various materials.

How to use lasers

All lasers utilize a form of computer numeric control (CNC) and have a similar workflow. When working with any CNC environ­ment, it’s important to understand the two main graphic files used by computers: raster or bitmap; and vector images.

A raster or bitmap image is composed of small dots called pixels, which are arranged to produce the design somewhat like build­ing blocks. These images are the most common file types available online. Raster images are most often manipulated using photo edit­ing software. Some of the most common file types are jpg, gif, png, tif and bmp. If you were to attempt to laser these types of images you would actually not cut smooth lines, but produce sawtooth-like steps. Most CNC machines can’t work in raster mode and in order to machine a raster image you’ll likely need to convert it to a vector image.
A vector image, on the other hand, is composed of smooth lines that are scalable. This means that however large or small you make the image, it will maintain its line characteristics. Most graphical design software titles (Adobe Illustrator, Corel Draw and Microsoft Publisher) will produce vector images with common output types such as eps, ai, cdr, wmf, emf. Additionally, most computer-aided design (CAD) software titles are capable of producing vector files; dxf files being the most common type.

There are two primary laser work types: engraving (“burning”) or cutting. Lasers can either “burn” image files (jpg, tiff, png, etc.) directly onto a variety of materials, or can either engrave or cut vec­tor files which have defined boundaries.

In order to engrave an image, you must first import your image file into the laser software or print to the laser from a compatible graphic design software (like Corel Draw or Adobe Illustrator) and establish its characteristics like size and orientation. (If work­ing with transparent material, it’s preferable to invert all files and work on the back of the material.) When ready to run your proj­ect, the software will scan the image and alter the laser’s intensity to reproduce a monochromatic version of the image on your desired material. While the software calculates the laser inten­sity values, you’ll have the ability to adjust the maximum laser strength. Typically, it’s recommended not to run a laser at more than 80% of its maximum power, as this will decrease the lifes­pan of the laser. You can alter the laser speed as well to affect the project’s overall intensity. Generally, the slower the speed, the darker the image. There is definitely a “sweet spot” of set­tings which, with experimentation and experience, you’ll find for your machine. Typically, users will create test boards showing the results of various settings.

If you’re looking to engrave or cut a project with a defined edge, a vector file will produce the best results. You can choose to do this from scratch using a palette of drawing tools common to most computer design software, or you can use an “image to vector” conversion tool which can be done in the same laser software or as a dedicated application. Using one of these tools is as simple as opening your image file, selecting the colours or shades you want to define your shape, and pressing a button. The software cre­ates a vector approximation, or “trace,” of the image. At this point you can preview your job and determine if any touch-up work is required.

What will you make?

The final and most important consideration when using lasers is, what are you going to make? Lasers have an incredible accuracy with almost no kerf. This makes lasers capable of some extremely delicate and intricate work. When cutting remember that, depend­ing on your laser’s power, there is a maximum thickness that you’ll be capable of cutting. I suggest stacking layers of material to achieve cumulative thickness which also allows for multiple artistic planes. Lasers provide an easy and quick way to brand or personal­ize all manner of projects that could make excellent gifts.

In speaking with countless laser users, I have heard time and time again of how they never could have imagined all of the dif­ferent projects they accomplish with a laser. It reminds me of the saying, “If all you have is a hammer, everything looks like a nail.” The same applies for a laser. Once you complete one project, you’ll quickly see how your imagination is the only limit to a laser’s possibilities.